01 rn31542en10gla0 wcdma fundamentals

7/27/2019 01 RN31542EN10GLA0 WCDMA Fundamentals

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WCDMA Fundamentals

1 © NSN Siemens Networks 3G Radio Planning Essentials / NPO Capability Development

3GRPESS – MODULE 1



Module 1 – WCDMA Fundamentals

Objectives

• After this module the participant shall be able to:-

• Understand the main cellular standards and allocatedfrequency bands

• Understand the main properties of WCDMA air interface


• Recognize the main NSN RRM functions and their maintasks



Module Contents

• Standardisation and frequency bands

• Main properties of UMTS Air Interface

• Overview of NSN Radio Resource Management (RRM)


• HSPA technology



Module Contents


– Standardisation of 3G cellular networks

– IMT-2000 frequency allocations

– UMTS – FDD Frequency band evolution

• Main ro er ies of UMTS Air In erface



• HSPA technology



Standardisation of 3G cellular networks

• ITU (Global guidelines and recommendations)

– IMT-2000: Global standard for third generation (3G) wireless communications

• 3GPP is a co-operation between standardisation bodies

ETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA (South Korea) – GSM

▪ EDGE

– UMTS


▪ -

▪ WCDMA - TDD

– TD-SCDMA

• 3GPP2 is a co-operation between standardisation bodiesARIB/TTC (Japan), CCSA (China), TIA (North America) and TTA (South Korea)

– CDMA2000▪ CDMA2000 1x

▪ CDMA2000 1xEV-DO



IMT-2000 frequency allocations

2200 MHz20001900 1950 2050 2100 21501850

ITU M o b i l e

S a t e l l i t e

IMT-2000 IMT-2000

EuropeUMTS(FDD) D

E C T

U M T S ( T D D )

GSM1800

M T S ( T D D )

UMTS(FDD)

M o b i l e

S a t e l l i t e

M o b i l e

S a t e l l i t e

M o b i l e

S a t e l l i t e


JapanIMT-2000 P H S

IMT-2000

USA P C S

u n l i c e n s e d

PCSPCS

U M T S ( T D D )

I M T - 2 0 0 0 ( T D D )

M o b i l e

S a t e l l i t e

M o b i l e

S a t e l l i t e

M o b i l e

S a t e l l i t e

M o b i l e

S a t e l l i t e



UMTS – FDD Frequency band evolution

• Release 99 – I 1920 – 1980 MHz 2110 –2170 MHz UMTS only in Europe, Japan – II 1850 –1910 MHz 1930 –1990 MHz US PCS, GSM1900

• New in Release 5 – III 1710-1785 MHz 1805-1880 MHz GSM1800

• New in Release 6 – IV 1710-1755 MHz 2110-2155 MHz US 2.1 GHz band – V 824-849MHz 869-894MHz US cellular, GSM850 – - -


• New in Release 7 – VII 2500-2570 MHz 2620-2690 MHz – VIII 880-915 MHz 925-960 MHz GSM900 – IX 1749.9-1784.9 MHz 1844.9-1879.9 MHz Japan

Not supported by RU10 RAN



Module Contents



– UMTS Air interface technologies

– WCDMA – FDD

– WCDMA vs. GSM

–


– Processing gain

– WCDMA codes and bit rates


• HSPA technology



UMTS Air Interface technologies

• UMTS Air interface is built based on two technological solutions

– WCDMA – FDD

– WCDMA – TDD

• WCDMA – FDD is the more widely used solution

– FDD: Separate UL and DL frequency band

• WCDMA – TDD echnolo is c rren l sed in limi ed n mber of


networks – TDD: UL and DL separated by time, utilizing same frequency

• Both technologies have own dedicated frequency bands

• This course concentrates on design principles of WCDMA – FDDsolution, basic planning principles apply to both technologies



WCDMA – FDD technology

• Multiple access technology is wideband CDMA (WCDMA)

– All cells at same carrier frequency

– Spreading codes used to separate cells and users

– Signal bandwidth 3.84 MHz

• M l i le carriers can be sed o increase ca aci


– Inter-Frequency functionality to support mobility between frequencies

• Compatibility with GSM technology

– Inter-System functionality to support mobility between GSM and UMTS



WCDMA Technology

5 MHz

3.84 MHz

f

F r e q u e n c y

WCDMA Carrier Users share same time and frequency


5+5 MHz in FDD mode5 MHz in TDD mode

me

Direct Sequence (DS) CDMA

WCDMAWCDMA55 MHz,MHz, 11 carriercarrier

TDMA (GSM)TDMA (GSM)55 MHz,MHz, 2525 carrierscarriers



UMTS & GSM Network Planning

GSM900/1800: 3G (WCDMA):




Differences between WCDMA & GSM

WCDMA GSM

Carrier spacing 5 MHz 200 kHz

Frequency reuse factor 1 1–18

Power controlfrequency

1500 Hz 2 Hz or lower

Quality control Radio resourcemanagement algorithms

Network planning(frequency planning)

High bit rates


requency vers ty z an w t g ves

multipath diversity withRake receiver

requency opp ng

Packet data Load-based packetscheduling

Timeslot basedscheduling with GPRS

Downlink transmit

diversity

Supported for

improving downlinkcapacity

Not supported by the

standard, but can beapplied

Services withDifferent qualityrequirements

Efficient

packet data



Multiple WCDMA carriers – Layered network

F3

1 - 10 km


F1

F2

F2

F3

F3

Micro BTSMacro BTS

Pico BTSs

50 - 100 m200 - 500 m



Spreading Code

Bits (In this drawing, 1 bit = 8 Chips SF=8)

Baseband Data+1

+1

-1

-1

ChipChip

CDMA principle - Chips & Bits & Symbols


Spread Signal

Data

Air Interface

-1

+1

+1

+1

-1

-1



Energy Box

Originating Bit Received Bit Energy per bit = E b = const


Duration (t = 1/R b )

Higher spreading factorWider frequency band Lower power spectral density

BUT

Same Energy per Bit



o w e r

d e n s

i t y ( W a

t t s / H z

)

Unspread narrowband signal Spread wideband signal

User bitrate

R

Spreading & Processing Gain


Frequency P

Bandwidth W (3.84 Mchip/sec)

sec84.3

Mchipconst W ==

[ ] )log(.10 R

W dBG p =Processing gain:



Voice user (R=12,2 kbit/s)

P o w e r d e n s i t y ( W / H z )

R

Gp=W/R=24.98 dB

• Spreading sequences

Processing Gain Examples


Frequency (Hz)

Packet data user (R=384 kbit/s)

Frequency (Hz)

P o w e r d e n s i t y ( W / H

z )

R

Gp=W/R=10 dB

have a different length• Processing gaindepends on the userdata rate



Transmission Power

Frequency

Power densityHigh bit rate user


5MHz

Time

Low bit rate user



WCDMA Codes

• In WCDMA two separate codes are used in the spreadingoperation

– Channelisation code

– Scrambling code

• Channelisation code


– DL: separates physical channels of different users and common channels,defines physical channel bit rate

– UL: separates physical channels of one user, defines physical channel bitrate

• Scrambling code – DL: separates cells in same carrier frequency

– UL: separates users



DL Spreading and Multiplexing in WCDMA

BCCH

Pilot X

CODE 1

X

CODE 2

CODE 3SUM

User 2

User 1

BCCH

Pilot

Radio frame = 15 time slots

User 3

CHANNELISATION codes:

P-CPICH

P-CCPCH


User 3

User 2

User 1 X

X

CODE 4

X

CODE 5

+

X

SCRAMBLINGCODE

RF

Time

3.84 MHzRF carrier

3.84 MHz bandwidth

DPCH1

DPCH2

DPCH3



DL & UL Channelisation Codes

• Walsh-Hadamard codes: orthogonal variable spreading factor codes (OVSFcodes) – SF for the DL transmission in FDD mode = {4, 8, 16, 32, 64, 128, 256, 512}

– SF for the UL transmission in FDD mode = {4, 8, 16, 32, 64, 128, 256}• Good orthogonality properties: cross correlation value for each code pair in the

code set equals 0

– In theoretical environment users of one cell do not interfere each other in DL


– In practical multipath environment orthogonality is partly lost Interference betweenusers of same cell

• Orthogonal codes are suited for channel separation, where synchronisationbetween different channels can be guaranteed

– Downlink channels under one cell

– Uplink channels from a single user

• Orthogonal codes have bad auto correlation properties and thus not suited in anasynchronous environment

– Scrambling code required to separate signals between cells in DL and users in UL



Channelisation Code Tree

C2(0)=[11]

C4(0)=[1111]

C4(1)=[11-1-1]

C8(0)=[11111111]

C8(1)=[1111-1-1-1-1]

C8(2)=[11-1-111-1-1]

C16(0)=[............]

C16(1)=[............]

C16(5)=[............]

C16(4)=[............]

C16(3)=[............]

C16

(2)=[............]

SF=1 SF=2 SF=4 SF=8 SF=16 SF=256 SF=512...


C0(0)=[1]

C2(1)=[1-1]

C4(2)=[1-11-1]

C4(3)=[1-1-11]

C8(3)=[11-1-1-1-111]

C8(0)=[1-11-11-11-1]

C8(5)=[1-11-1-11-11]

C8(6)=[1-1-111-1-11]

C8(7)=[1-1-11-111-1]C16(15)=[...........]

C16(14)=[...........]

C16(13=[...........]

C16(12)=[...........]C16(11)=[...........]

C16(10)=[...........]

C16(9)=[............]

C16(8)=[............]

C16(7)=[............]

16 6 = ............



Spreadingfactor

Channelsymbol

rate(ksps)

Channel bitrate

(kbps)

DPDCHchannel bitrate range

(kbps)

Maximum userdata rate with ½-

rate coding(approx.)

512 7.5 15 3–6 1–3 kbps256 15 30 12–24 6–12 kbps128 30 60 42–51 20–24 kbps64 60 120 90 45 kbps32 120 240 210 105 kb s

Half rate speech

Full rate speech

Physical Layer Bit Rates (DL)


16 240 480 432 215 kbps8 480 960 912 456 kbps4 960 1920 1872 936 kbps

4, with 3parallel

codes

2880 5760 5616 2.3 Mbps

128 kbps

384 kbps

2 Mbps

Symbol phyb R R ⋅= 2_SF

W RSymbol =

(QPSK modulation)



Physical Layer Bit Rates (DL) - HSDPA

• 3GPP Release 5 standards introduced enhanced DL bit rates withHigh Speed Downlink Packet Access (HSDPA) technology

– Shared high bit rate channel between users – High peak bit rates

– Simultaneous usage of up to 15 DL channelisation codes (In HSDPA SF=16)

– Higher order modulation scheme (16-QAM) Higher bit rate in same band

▪ 16-QAM provides 4 bits per symbol 960 kbit/s / code physical channel peak


Coding rate

QPSK

Coding rate

1/4

2/4

3/4

5 codes 10 codes 15 codes

600 kbps 1.2 Mbps 1.8 Mbps

1.2 Mbps 2.4 Mbps 3.6 Mbps


16QAM

2/4

3/4

4/4




HSDPA



Physical Layer Bit Rates (UL) - HSUPA

• 3GPP Release 6 standards introduced enhanced UL bit rates withHigh Speed Downlink Packet Access (HSUPA) technology

– Fast allocation of available UL capacity for users – High peak bit rates

– Simultaneous usage of up to 2+2 UL channelisation codes (In HSUPA SF=2 – 4)


Coding rate

1/2

3/4

4/4

1 x SF4 2 x SF4 2 x SF2

2 x SF4480 kbps 960 kbps 1.92 Mbps 2.88 Mbps

720 kbps 1.46 Mbps 2.88 Mbps 4.32 Mbps

960 kbps 1.92 Mbps 3.84 Mbps 5.76 Mbps



DL & UL Scrambling Codes

DL Scrambling Codes

• Pseudo noise codes used for cell separation

– 512 Primary Scrambling Codes

UL Scrambling Codes

•


– Long scrambling codes of length of 38 400 chips = 10 ms radio frame

– Short scrambling codes of length of 256 chips are periodically repeated toget the scrambling code of the frame length

▪ Short codes enable advanced receiver structures in future



Scrambling Codes & Multipath Propagation

Scramblingcode C1


Scramblingcode C2

C1+∆2

UE has simultaneous connectionto two cells (soft handover)



RAKE Receiver

Rx

Output

FingerCell-1

Cell-1

Cell-1

Rx

Rx

Finger

Finger


• Combination or multipath components and in DL also signals from different cells

D e l a

y ∆ 1

Code usedfor the

connection

t

Cell-2Rx Finger

D e l a

y ∆ 2

D e l a

y ∆ 3



Channelisation code Scrambling code

Usage Uplink: Separation of physical data

(DPDCH) and control channels

(DPCCH) from same terminal

Downlink: Separation of downlinkconnections to different users within one

cell

Uplink: Separation of mobile

Downlink: Separation of sectors (cells)

Length 4–256 chips (1.0–66.7 µs)

Downlink also 512 chips

Uplink: (1) 10 ms = 38400 chips or (2)

66.7 µs = 256 chips

Channelisation and Scrambling Codes


Different bit rates by changing the lengthof the code

Option (2) can be used with advanced

base station receivers

Downlink: 10 ms = 38400 chips

Number of codes Number of codes under one scrambling

code = spreading factor

Uplink: 16.8 million

Downlink: 512

Code family Orthogonal Variable Spreading Factor Long 10 ms code: Gold code

Short code: Extended S(2) code family

Spreading Yes, increases transmission bandwidth No, does not affect transmission

bandwidth



Module Contents




– Load control


–

– Packet Scheduler

– Resource Manager

– Power Control

– Handover Control

• HSPA technology



Radio Resource Management

• RRM is responsible for optimal utilisation of the radio resources:

– Transmission power and interference

– Logical codes

• The trade-off between capacity, coverage and quality is done allthe time

– Minimum required quality for each user (nothing less and nothing more)


ax mum num er o users

• The radio resources are continuously monitored and optimised byseveral RRM functionalities service quality

cell coverage cell capacity

Optimizationand Tailoring



RRM Functionalities

LC Load Control

AC Admission Control

PS Packet Scheduler

RM Resource Manager

PC Power Control

LC

AC

For each cell

PS

RM


on ro

PC

HCFor each connection/user



• LC performs the function of load control in association with AC & PS

• LC updates load status using measurements & estimations provided by AC andPS

• Continuously feeds cell load information to PS and AC;

– Interference levels (UL)

Load Control (LC)


–

LC

AC

PSNRT load

oa c ange n o

Load status



Load Control – Load Status

• Load thresholds set by radio network planning parameters

Overloadthreshold x

Load Targetthreshold y

Load Margin

Overload


P o w e r

Time

Normal load

Measured loadFree capacity



• Checks that admitting a new user will not sacrifice plannedcoverage or quality of existing connections

• Admission control handles three main tasks

– Admission decision of new connections

▪ Take into account current load conditions (from LC) and load increase by the new

Admission Control (AC)


connection

▪ Real-time higher priority than non-real time

▪ In overload conditions new connections may be rejected

– Connection QoS definition

▪ Bit rate, BER target etc.

– Connection specific power allocation (Initial, maximum and minimum power)



Packet Scheduler (PS)

• PS allocates available capacity after real-time (RT) connections tonon-real time (NRT) connections

– Each cell separately

– Based on QoS priority level of the connection

– In overload conditions bit rates of NRT connections decreased


•PS selects allocated channel type (common, dedicated or HSPA)

• PS relies on up-to-date information from AC and LC

• Capacity allocated on a needs basis using ‘best effort’ approach

– RT higher priority



Resource Manager (RM)

• Responsible for managing the logical radio resources of the RNCin co-operation with AC and PS

• On request for resources, from either AC(RT) or PS(NRT), RM

allocates: – DL spreading code

– UL scrambling code


Code Type Uplink Downlink

Scrambling codes

Spreading codes

User separation Cell separation

Data & control channels from same UE Users within one cell



Power control (PC) in WCDMA

• Fast, accurate power control is of utmost importance – particularlyin UL;

– UEs transmit continuously on same frequency Always interference

between users – Poor PC leads to increased interference reduced capacity

• Every UE accessing network increases interference


– target to m n m se t e nter erence n m ze transm t power o eac

link while still maintaining the link quality (BER)

• Mitigates 'near far effect‘ in UL by providing minimum requiredpower for each connection

• Power control has to be fast enough to follow changes inpropagation conditions (fading)

– Step up/down 1500 times/second

U li k l



Uplink power control target

Minimise required UL received power minimised UL transmit power and interference

min(Prx1)

min(Prx2)

&

About e ual when

Target:


UE1 UE2

Rb1

= Rb2

Ptx1

Ptx1

P C t l t



Power Control types

• Power control functionality can be divided to three main types

•Open loop power control

– Initial power calculation based on DL pilot level/pathloss measurement by UE

• Outer (closed) loop power control


– ,

target – RF quality target (SIR target) setting for fast closed loop PC based on

connection quality

• Fast closed loop power control

– Radio link RF quality (SIR) measurement and comparison to RF qualitytarget (SIR target)

– Power control command transmission based on RF quality evaluation

– Change of transmit power according to received power control command

P C t l t



Open Loop Power Control (Initial Access)

MS

Power Control types


UL Outer LoopPower Control

Closed Loop Power Control

RNCBSDL Outer LoopPower Control

BLER target

Power control in HSPA



Power control in HSPA

• In HSDPA (DL) the transmit power from base station is keptconstant and the signal modulation and coding is adaptedaccording to the channel conditions

– 2 ms interval 500 Hz

• In HSUPA (UL)


– The power control of HSUPA channels in UL utilises both

▪ Fast closed loop power control

▪ Outer loop power control

– Both work according to similar principles as the R99 power control

Handover Control (HC)



Handover Control (HC)

• HC is responsible for:

– Managing the mobility aspects of an RRC connection as UE moves around thenetwork coverage area

– Maintaining high capacity by ensuring UE is always served by strongest cell

• Soft handover

– MS handover between different base stations


• Softer handover – MS handover within one base station but between different sectors

• Hard handover

– MS handover between different frequencies or between WCDMA and GSM

Soft/softer handover



Soft/softer handover

• UE is simultaneously connected to 2 to 3 cells during soft handover

• Soft handover is performed based on UE cell pilot power measurements andhandover thresholds set by radio network planning parameters

• Radio link performance is improved during soft handover• Soft handover consumes base station and transmission resources

BS1


BS1

BS2

BS3 R e c e i v e d s i g n a l s t r e n g t h

BS3

Distance from BS1

Threshold

Soft handover

BS2

Hard handover



Hard handover

Hard handovers are typically performed between WCDMAfrequencies and between WCDMA and GSM cells

GSM/GPRSGSM/GPRS

Inter-System handovers (ISHO)


f1

f2

f1

f2f2f2

Inter-Frequency handovers (IFHO)

Module Contents



Module Contents





• HSPA technology

Module Contents



Module Contents

HSPA technology

• Channel types

• Physical Channels

• Principle of HSPA


Channel Types for User Plane Data (R99)



Node B

d D o w n

l i n k

d C h a n n e l s

The introduction of 3G made use of uplink anddownlink dedicated channels to transfer userplane and control plane data in CELL_DCH

Applicable to

• All 3GPP Releases



U p

l i n k

a

D e

d i c a

t e

Uplink air-interface capacity defined bymaximum planned increase in uplinkinterference

Downlink air-interface capacity defined bydownlink transmit power capability

Cell_DCH

CS and PS services




Node B

In R5 3G evolved to include HSDPA fortransferring packet switched user plane data inthe downlink direction

Applicable to

• 3GPP Release 05• NSN RAS05, RAS05.1

HSDPA makes use of a downlink transmit power e d i c a

t e d

n n e

l s

D P A



a ocat on an so as a rect mpact upon

downlink capacity

The resource shared between multiple HSDPAusers is the HSDPA downlink transmit power

The Node B scheduler assigns timeslots &

codes to specific UE to allow access to theHSDPA downlink transmit power

U p l i n

k

C

h

Cell_DCH

H

PS services CS services continue to use R99 dedicated channels




Node B

• 3G has further evolved to include HSUPA fortransferring packet switched user plane data inthe uplink direction

• Applicable to

– 3GPP Release 06 – NSN RAS06, RU10

• HSUPA makes use of a uplink interference U P A

D P A



uplink capacity• The resource shared between multiple

HSUPA users is the uplink interference

• The Node B scheduler assigns transmit power

ratios to specific UE to allow a contributiontowards the total increase in uplink interference

H

Cell_DCH

H

PS services CS services continue to use R99 dedicated channels

Module Contents



Module Contents

HSPA technology

• Channel types




Physical Channels for R99 UE



Node B

UL CHANNELSDPCH includes

• DPDCH• DPCCH – Pilot, TFCI, FBI, TPC

DPDCH encapsulates• Signalling radio bearers• User plane radio bearersR99 DPCH

y


D P D C H

D P C C H

DL CHANNELSDPCH includes

• DPDCH• DPCCH - Pilot, TFCI, TPC

DPDCH encapsulates• Signalling radio bearers• User plane radio bearers

D P D C H

D P C C H

Dedicated

Physical Channels for Rel5 / Rel6 HSDPA UE



Node B

UL CHANNELSDPCH includes

• DPDCH• DPCCH – Pilot, TFCI, FBI, TPC• HS-DPCCH – CQI, ACK/NACK

DPDCH encapsulates• Signalling radio bearers• User plane radio bearers

DL CHANNELS

C H

C H

HSDPAAssociated DPCH

y


DPCH includes

• DPDCH• DPCCH - Pilot, TFCI, TPC

DPDCH encapsulates• Signalling radio bearers

HS-PDSCH encapsulates• User plane radio bearers

HS-SCCH provides• Channelisation code set, modulation scheme,

transport block size, HARQ process, redundancyand constellation version, new data indicator, UEidentity

1 - 1

5 x H S - P

D

1 - 4 x

H S - S

D P D C

H

D P C C

H

H S - D P C

C

D P D C

H

D P C C

H

Dedicated Common

Physical Channels for Rel6 HSPA UE (UL)



Node B

C H

H C H

H

H

UL CHANNELS

E-DPCH includes• E-DPDCH• E-DPCCH – E-TFCI, RSN, Happy Bit

DPCH includes

• DPDCH• DPCCH – Pilot, TFCI, FBI, TPC• HS-DPCCH – CQI, ACK/NACK

E-DPDCH encapsulates

y ( )


1 - 1

5 x

H S - P

D

1 - 4 x

H S - S

C

D P D C

H

D P C C

H

H S - D

P C

C

1 , 2 , 4

x E - D

P D

E - D

P C C H

F - D

P C

H

Dedicated Common

E - D

C H R G C

E - D

C H A G C

E - D

C H H

I C•

DPDCH encapsulates• Signalling radio bearers

Physical Channels for Rel6 HSPA UE (DL)



Node B

H H H

DL CHANNELS

DPCH includes• F-DPCH – TPC• E-DCH RGCH• E-DCH HICH

E-DCH AGCH encapsulates

• Absolute grant value, absolute grant scope

HS-PDSCH enca sulates

y ( )


1 - 1

5 x

H S - P

D S

1 - 3 x

H S - S

C C

D P D C H

D P C C H

H S - D

P C C H

1 , 2 , 4

x E - D P

D

E - D

P C C

H

F - D

P C H

Dedicated Common

E - D

C H R G

C

E - D

C H A G

C

E - D

C H H I C

• User plane radio bearers

HS-SCCH provides• Channelisation code set, modulation

scheme, transport block size, HARQprocess, redundancy and constellationversion, new data indicator, UE identity

Module Contents



HSPA technology

• Channel types




HSxPA Motivation and General Principle



Improved performance and spectral efficiency in DL and UL by introducing a shared channel principle:• Significant enchancement with peak rates up to 14.4 Mbps (28 Mbps in Rel7) in DL, and 2

Mbps (11.5 Mbps with 16QAM) in UL

• Huge capacity increase per site; no site pre-planning necessary

• Improved end user experience: reduced delay/latency, high response time


HSDPA (3GPP Rel5)

Fast pipe is shared among UEs

HSUPA (3GPP Rel6)

Dedicated pipe for every UE in ULPipe (codes and grants) changingwith timeE-DCH scheduling

Rel. 99

Dedicated pipe for every UE

HSDPA Overview



15 CodeShared

transmission

16QAMModulation

TTI = 2 ms Hybrid ARQwith incr. redundancy

Fast LinkAdaptation

AdvancedScheduling


BenefitHigher Downlink Peak rates: 14 Mbps

Higher Capacity: +100-200%

Reduced Latency: ~75 ms

HS-PDSCH Transmit power



Cell maximum TX

powerMaximum HSDPA

ower

PtxCell maximum TX powerPtx

The Packet Scheduler is responsible for determining the transmission power on the HS-PDSCH channels

• Dynamic HSDPA power allocation is always used in BTS – HSDPA power can be limited with PtxMaxHSDPA

• HSDPA Dynamic Resource Allocation feature is activated with RNC parameterHSDPADynamicResourceAllocation

– Disabled: PtxMaxHSDPA sent to BTS and used to limit the maximum HSDPA power

– Enabled: No power limitation sent to BTS, all available power allocated to HSDPA


• HSDPA power is limited by thePtxMaxHSDPA parameter

Common chs

HSDPA

(PtxMaxHSDPA)

Non-

HSDPA

power

Time Common chs

HSDPA

Non-HSDPA

power

Time

• HSDPA power is not limited, all availablepower can be allocated to HSDPA

• Still PtxMaxHSDPA can be used to limit

Maximum code allocation for HSDPA• Code tree limitation makes it hard to have 15 codes allocated for HSDPA



SF=1

SF=2

SF=4

• Code tree limitation makes it hard to have 15 codes allocated for HSDPA – Still commonly 14 or 12 or lower amounts are easily available

– Note that current terminals support only 10 codes so 15 codes means more than 1 users per TTI

• 15 codes is available but not commonly for cells where has reasonable high traffic (noticing terminallimitation 10 codes, thus fully utilise 15 codes needs minimum 2 HSDPA users)

– Case 1: Allocation of 15 is not possible when more than 2 HSDPA users are active (i.e. 3 HSDPA users) – Case 2: Allocation of 15 is not possible (with two HSDPA users) when 1 AMR12.2 user exists in the cell


SF=8

SF=16

SF=32

SF=64

SF=128

SF=256

15 HS-PDSCH codes

Up to three HS-SCCH codes

Codes for commonchannels in the cell

Codes for associated DCHs andnon-HSDPA users

Used by 2 HSDPA UEs no SF256available for the 3rd UE for

associated DCH

Used by AMR user only oneSF128 code remains for associated

DCH

Used by HSDPA UE as associated DCH and HS-SCCH

Case1:

Case2:

Case1+2:

HSDPA - UE Categories



• QPSK and 16QAM modulation with multicode transmission used to achieve high data rates

• 12 different UE categories defined, categories are characterised by

– Number of parallel codes supported

– Minimum inter-TTI interval

• Theoretical peak bit rate up to 14.4 Mbps for category 10 UE using 15 codes and 16QAM


HSDPA Code Multiplexing HS-SCCH



HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

• With Code Multiplexing, maximum of three UEscan be scheduled during one TTI from singlecell

• Multiple HS-SCCH channels (max 3 in RAS06) – One for each simultaneously receiving UE

• Available HS-PDSCH codes and HS-PDSCHpower of cell are divided between UEs

• -

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-SCCH

HS-SCCH


channel conditions of a UE

• Important when cell supports more codes thanUEs do – Cell supports 15 HS-PDSCH codes, Cat6

and Cat8 UEs => 3 users can be scheduledon TTI

• BTS must also be capable of 10/15 codes inorder to dynamically adjust HS-PDSCH codes

cat 6

-

HS-PDSCH

cat 6 cat 6 cat 6cat 8

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HSUPA Overview



TTI = 10 ms1-4 CodeMulti-Code

transmission

FastPower Control

Hybrid ARQwith incr. redundancy

NodeBControlledScheduling


BenefitHigher Uplink Peak rates: 2.0 Mbps

Higher Capacity: +50-100%

Reduced Latency: ~50-75 ms

HSUPA - UE Categories



• BPSK modulation with multicode transmission used to achieve high data rates• 6 different UE categories defined, categories are characterised by

– Number of parallel codes supported

– Support of 2ms TTI - 10ms TTI supported by all the HSUPA UEs

• Theoretical peak bit rate up to 5.74 Mbps for category 6 UE using 2 ms TTI

– No coding and no retransmissions - all bits must be delivered correctly over the air…

TransportBlock size

HSUPACategory

TTICodes x Spreading Data rate


11484

20000

20000

5772

20000

14484

2798

14484

7110

2 Mbps102 x SF24

2.89 Mbps22 x SF24

1.45 Mbps102 x SF42

1.40 Mbps22 x SF42

2 Mbps102xSF2 + 2xSF46

6

5

3

1

2

10

10

10

2xSF2 + 2xSF4

2 x SF2

2 x SF4

1 x SF4

5.74 Mbps

2 Mbps

1.45 Mbps

0.71 Mbps

HSPA mobility



HSDPA

• Soft handover on associated DCH channels (signalling, UL data)

• Serving cell change for HSDPA data channel

– Connected only to one cell at a time

Notice that soft/softer handoveris not supported for HS-SCCH/HS-PDSCH


HSUPA

• Soft handover utilised for uplink channels as required due to near-far problem

• Only Serving Cell can allocate more UL capacity/power

-

HS-PDSCHDPCH

DPCHServingHS-DSCH cell



Module 1 – WCDMA Fundamentals



Summary

• Radio interface technology of UMTS is WCDMA with FDD and TDDversions

• WCDMA networks can be built on European, US-based andAsian/Japanese frequency bands

• WCDMA air interface utilises combination of two spreading codes


radio resources while offering required quality of service to users• HSPA technology can provide higher air interface efficiency

01 rn31542en10gla0 wcdma fundamentals

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